[LARTC] prio/pref weirdness

[LARTC] prio/pref weirdness

[Mihai RUSU]

Hi

I am playing with filters and cbq/htb and I have found this strange thing.
Add some filters using the prio/pref (they seem an alias to me)
parameter like:
tc filter add dev eth0 protocol ip parent 1: pref 5 u32 match ip dst 1.2.3.4
tc filter add dev eth0 protocol ip parent 1: pref 10 u32 match ip dst 2.3.4.5

And try tc filter show dev eth0, you will see that every filter you have
is multiplied by the number of different prio/pref values you have used.

Thus it looks like you would do this:

tc filter add dev eth0 protocol ip parent 1: pref 5 u32 match ip dst 1.2.3.4
tc filter add dev eth0 protocol ip parent 1: pref 5 u32 match ip dst 2.3.4.5

tc filter add dev eth0 protocol ip parent 1: pref 10 u32 match ip dst 1.2.3.4
tc filter add dev eth0 protocol ip parent 1: pref 10 u32 match ip dst 2.3.4.5

Why is that? Is it a tc bug? Or is it normal? What it happens if I use
filters of different pref/prio ? In which order are they checked ?


Thanks

----------------------------
Mihai RUSU

Disclaimer: Any views or opinions presented within this e-mail are solely
those of the author and do not necessarily represent those of any company,
unless otherwise specifically stated.

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Re: [LARTC] prio/pref weirdness

[Martin Devera]

It is bug I described a year ago. It is due to a bit ... weird
system used in tc filters and u32. There is global table of
all u32 hashed and it is looked up for each filter id - thus 
it will display them over and over ....
You can mitigate it by using "show pref N" so see only part
you are interested in.
devik

On Mon, 8 Apr 2002, Mihai RUSU wrote:

> Hi
> 
> I am playing with filters and cbq/htb and I have found this strange thing.
> Add some filters using the prio/pref (they seem an alias to me)
> parameter like:
> tc filter add dev eth0 protocol ip parent 1: pref 5 u32 match ip dst 1.2.3.4
> tc filter add dev eth0 protocol ip parent 1: pref 10 u32 match ip dst 2.3.4.5
> 
> And try tc filter show dev eth0, you will see that every filter you have
> is multiplied by the number of different prio/pref values you have used.
> 
> Thus it looks like you would do this:
> 
> tc filter add dev eth0 protocol ip parent 1: pref 5 u32 match ip dst 1.2.3.4
> tc filter add dev eth0 protocol ip parent 1: pref 5 u32 match ip dst 2.3.4.5
> 
> tc filter add dev eth0 protocol ip parent 1: pref 10 u32 match ip dst 1.2.3.4
> tc filter add dev eth0 protocol ip parent 1: pref 10 u32 match ip dst 2.3.4.5
> 
> Why is that? Is it a tc bug? Or is it normal? What it happens if I use
> filters of different pref/prio ? In which order are they checked ?
> 
> 
> Thanks
> 
> ----------------------------
> Mihai RUSU
> 
> Disclaimer: Any views or opinions presented within this e-mail are solely
> those of the author and do not necessarily represent those of any company,
> unless otherwise specifically stated.
> 
> _______________________________________________
> LARTC mailing list / LARTC@mailman.ds9a.nl
> http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/
> 
> 

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Re: [LARTC] prio/pref weirdness

[Mihai RUSU]

On Mon, 8 Apr 2002, Martin Devera wrote:

> It is bug I described a year ago. It is due to a bit ... weird
> system used in tc filters and u32. There is global table of
> all u32 hashed and it is looked up for each filter id - thus
> it will display them over and over ....
> You can mitigate it by using "show pref N" so see only part
> you are interested in.
> devik
>

Thanks for the answer.
Now correct me if I got it right, what you said it is a tc bug? Because it
looks for the filters like you said ? I mean the kernel doesnt have all
those filters, right?

----------------------------
Mihai RUSU

Disclaimer: Any views or opinions presented within this e-mail are solely
those of the author and do not necessarily represent those of any company,
unless otherwise specifically stated.

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Re: [LARTC] prio/pref weirdness

[Martin Devera]

> Thanks for the answer.
> Now correct me if I got it right, what you said it is a tc bug? Because it
> looks for the filters like you said ? I mean the kernel doesnt have all
> those filters, right?

well it is really bug in kernel in show part. But yes it is
only cosmetic bug - kernel have only one copy of it. It only
displays it more times.
devik

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